Daniel Levitin's new book The World in Six Songs has attracted a serious fan following, including Sting, Joni Mitchell and Willie Nelson. Neuroscientist, rock producer, and best selling author (This is Your Brain on Music) Levitin talks about his research for this fascinating book that takes the reader on a journey of the world through 6 types of songs--friendship, joy, comfort, knowledge, religion/ritual, and love.